The thyroid is a small butterfly shape gland which sits on top of the windpipe in the midline of the base of the neck. It is responsible for secreting hormones which help regulate the rate of the chemical reactions in the body. There are two main problems that can happen with the thyroid gland:
1) it can produce too much or too little hormone
2) nodules can develop within it.
High or low levels of thyroid hormone
Too little hormone (hypothyroidism) can cause tiredness, constipation, slow heart rate, depression, and weight gain. This can easily be treated by giving the patient thyroid hormone replacement tablets (levothyroxine) on a daily basis.
Too much hormone causes a rapid or irregular heartbeat, palpitations, anxiety, weight loss, feeling hot, and diarrhoea. The patient is referred to an endocrinology doctor who can prescribe medications (commonly carbimazole) to help suppress this hormone production. This is often a temporary solution. Once the medications are stopped the thyroid might produce too much hormone again. At this stage, the endocrinologist will refer the patient to me for surgery to remove part or all of the gland (thyroidectomy). An alternative to surgery would be having radioactive iodine therapy to destroy the gland.
I would normally order Free T3, Free T4, TSH and thyroid peroxidase antibody blood tests.
The patient will need an ultrasound scan to check for nodules in the thyroid. If nodules are detected they may need a biopsy (fine needle aspiration) to check for cancer. Some nodules can secrete excessive thyroid hormone (toxic nodules). A technetium-99 scan can be done and this can identify “hot nodules”. If there is a hot nodule on one side of the thyroid gland, the patient can have removal of half of the thyroid gland containing the hot nodule. If the technetium scan shows diffuse changes in the thyroid or there are no nodules, then a total thyroidectomy would be recommended. This involves removal of the entire thyroid gland.
Nodules
The vast majority of thyroid nodules are benign (non-cancerous). If I was to scan the thyroid glands of the whole population, a large proportion would have nodules. It would be unsustainable to investigate all the nodules in the whole population, so we tend not to investigate nodules smaller than a centimetre in diameter. General practitioners or endocrinologists refer patients with nodules to me. Patients can also book in to see me directly, privately. Large nodules may press on the windpipe causing shortness of breath. This is a “compressive symptom”. If the thyroid is big enough, it can be unsightly. This is a “cosmetic symptom”. Both these are reasons to perform a thyroidectomy to remove some, or all, of the gland. Some patients have a family history of thyroid cancer (eg. medullary thyroid cancer). Radiotherapy (or high dose radiation) to the neck can put you at a higher risk of thyroid cancer.
Once I have asked you about these symptoms and about your medical history, medications and allergies, I examine your mouth, throat, nose and neck. I use a camera (flexible nasendoscope), inserted in your nose, to examine your throat and vocal cords to check they are moving. The thyroid gland sits next to nerves that move the vocal cords. A thyroid cancer can damage one of these nerves, paralysing the vocal cord and causing hoarseness. I also check if the thyroid gland is growing downwards, behind the breast bone, making it more challenging to remove during surgery. I also check if there are any enlarged lymph nodes in the neck. Some thyroid cancers spread to the lymph nodes in the neck. A lump in the thyroid and in the neck would be highly suspicious for thyroid cancer.
I would normally order an ultrasound and fine needle aspirate. The ultrasound is performed by a doctor or radiographer who has trained specially in the technique. It is possible to look at the thyroid nodules and look at their shape and appearance. The nodules are categorised on a scale from 1 to 5:
U1 normal thyroid
U2 benign
U3 indeterminate
U4 suspicious of cancer
U5 definitely cancer
Nodules which are U3, U4 or U5 are normally subjected to fine needle aspiration. This means that the ultrasound probe is used to guide a needle into the nodule of interest to take a few cells out of which can be smeared on a slide. Alternatively, a thicker needle may be used to take a core of tissue out of the nodule. The slide can be examined under the microscope and classified according to a grading system:
Thy1 inadequate sample (unable to make a diagnosis)
Thy2 benign
Thy3a indeterminate lesion (repeat the test to reclassify into one of the other groups)
Thy3f follicular lesion – could be benign or cancerous
Thy4 suspicious of cancer
Thy5 definitely cancer
The combination of ultrasound and cell appearances, under the microscope, allow us to decide on the treatment of thyroid nodules. The results will never be 100% accurate and are operator dependent i.e. the accuracy depends on the experience of the radiologist or pathologist. If cancer is suspected, these tests are discussed in our team meeting, which comprises surgeons, pathologist, radiologists and oncologists (MDT meeting). U2 nodules are not normally treated unless they are pressing on the windpipe causing shortness of breath. If there are large nodules on one side of the thyroid, the half of the thyroid, containing these nodules, can be removed (hemithyroidectomy). If there are large nodules on both sides, the whole thyroid can be removed (total thyroidectomy).
Thy3f nodules on one side require a hemithyroidectomy. Thy3f nodules on both sides of the thyroid require a total thyroidectomy. Thy4 and Thy5 nodules need a thyroidectomy – either a total or hemithyroidectomy depending on the size of the nodules.
The thyroidectomy specimen is examined under the microscope to check for cancer. If cancer is found, your case is discussed in our head and neck cancer team meeting (MDT) to decide on additional treatment – which may involve a second operation to remove the rest of the gland, and/or radioactive iodine administration.
Most thyroid nodules, even cancerous ones are slow growing, so there is not the same degree of urgency to treat these nodules as other types of head and neck cancers. Indeed, in some countries, such as Japan, a cancerous thyroid nodule, diagnosed on fine needle aspiration, is sometimes watched with serial ultrasounds over a number of years. They can afford to do this because a majority of thyroid cancers are slow growing. In the UK, in general, we prefer to treat these nodules with surgery.
Hemithyroidectomy
You come into the hospital and have a general anaesthetic (are fully asleep). I make an incision low down in the midline of the neck (in an existing skin crease if possible). I expose the thyroid gland and take out half of the thyroid. I put this in a pot and send it off to the lab for analysis under the microscope. The results come back 2-3 weeks after the surgery. I stitch up the wound with absorbable stitches and put glue on top. The wound is raised and red on purpose and after a few months the wound flattens out.
This is how the scar should look 2 weeks after surgery
After a year, the scar becomes pale. Most patients don’t require a drain in the neck. The glue makes it waterproof. After surgery, you need one night in hospital and 2 weeks off work at home. This is to prevent the wound getting infected. I would suggest no heavy lifting or exercise for 4 weeks after surgery, but you must move your head from side to side, as far as possible, to avoid stiffness of your neck after the operation.
I sutured this patient's wound with a special Parisian wound closure technique after performing a thyroidectomy a few years ago. Can you see the incision?
After a couple of weeks, the glue turns grey and you can peel it off, or I can peel it off in clinic. I would normally see you between 2-6 weeks after the surgery. I examine the wound and use a camera placed through the nose to check the vocal cords are moving after the surgery. 6 weeks after surgery, you are sent for thyroid function blood tests to ensure the remaining half of the thyroid is producing enough thyroid hormone for the needs of the body.
The risks of the operation include: pain, bleeding, infection, general anaesthetic complications, collection of blood or fluid under the surface of the skin (which can be removed with a needle and syringe in clinic over a number of weeks), low thyroid hormone requiring tablets for life, hoarseness of voice (temporary or permanent), which is uncommon, because of damage, cutting or stretching of the recurrent laryngeal nerve, further surgery to remove the other side of the gland if cancer is found +/- radioactive iodine treatment, damage to the surrounding structures such as the trachea or oesophagus (rare), 20% risk of mortality if COVID positive during a general anaesthetic. If you contract COVID, this may result in a 7 week delay to surgery.
Total thyroidectomy
The whole of the gland is removed. You might need to stay more than one night if your post op blood tests show your calcium level in the blood has dropped. The operation and risks are the same except for additional risks of: bilateral vocal nerve damage/cutting causing shortness of breath requiring tracheostomy (exceedingly rare), low calcium requiring tablets temporarily or less commonly for life (a low calcium causes pins and needle or cramps in muscles – you need to go to A+E to have a blood test immediately if this happens). You will need to take thyroid hormone replacement tablets (levothyroxine) daily after surgery, for life, and need blood tests to check you are taking the correct dosage. You may need to take calcium tablets temporarily, or, less likely, permanently, after surgery.